Elastic-fluid turbine



'0. STEENSTRUP. ELASTIC FLUID TURBINE.

APPLIGATI'ON FILED FEB. I6, i920.

` Patented Sert. 21,1920

ZSHEETS-SHEET l l' l i HE .M mv

, lvenntor': Chr-is anSLeernstw-up, by n* sTEENsTRuP. ELASTIC FLUID TURBINE. APPLICATION FILED FEB. I6, I920.

vPatented Sept. 2 SHEETS--SHEET 2- a. o A

I I Inventor: y I

\ Chris imSteenstri-llnk ba. I' {ME/f HIE, Amor-neg CHRISTIANSTEENS'IRUP, OF SCHENECTADY, NEW YORK, ASSIGNOB/,TO GENERAL ELECTRICCOMPANY, A CORPORATON OF NEW' YQRK.- I

,mesmo-FLUID Tunisian.

1,553; roi.

Application filed February 16, 1920. SerialNoi 359,077.

'1'0 all w la om) it may coaccwt:

Beit known that I, CiiinsiriAN SiiinnTn s'iiiur, a citizen'ot the UnitedStates` residing at Schenectady, county of Schenectady, Stateof NewYork, have invented certain new land useful Improvements in Elastic-Fluid Turbines, of which the following is a I specification The: presentinvention' relates to elasticy i'uid turbines and particularly ytobucket or blade fasteninfr means.

*11n applyingqbuckets to a bucket-carrying element, for example, totherim of a turbine wheel, particularly when the Jfastening means is of theso-termed inverted dovetailed type, itis desirable that the adjacentsides of the bucket bases engage each other around the periphery vot they vwheel so tightly as to set' up stresses in the buckets of such amagnitude that when the wheel is rotating. the centrifugal forces set upwill not be sufficient to stretchv the buckets to an eX- tent whichwould cause the buckets to separate from each other around the wheel. lnother words, it 'is desirable thatthe sides of the bucket bases engageeach other with toms ofthe bucket i an improved Suiicient pressure toset up a tension in" the buckets themselves equivalent, at least, ltothe stress that will be applied by centrifugal "force when' the machineis in operation. Likewise, it is desirable that the botbases engage theannularA shoulders at the baseof the rim with sufficient pressure, sothat the stress set up is equivalent, at least, to the stress that willbe applied by centrifugal torce when the inachine iS in operation, sothat the bucket bases will not separate from the shoulders. However, itis essential, on the other hand, that initial stresses of too greatmagnitude should not be set up in the bucket ring when the buckets arebeing put on the wheel, as this may result in improper positioning ofthe buckets and in injury to the wheel. and to the buckets. y

The object or my invention is to provide structure and arrangementwhereby it is only possible'to set up' initial stresses in thebucketrings of a desired magnitude, and to this end ing stripsl along theedges of the buckets,

' or alongtheir bottoms, or both", which, when the stressesreach acertain value,

I provide crushf Specication ci" Letters Patent. Patent-.ed 21, '1920i`lFor a consideration of whatl believe to be novel and my invention,attentionis directed to the accompanying description and the claimsappended thereto.

in the drawing, Figure l is a radial sectional view ott a portion oiaturbine motor having bucket fastening means embodying my invention;Fig. 2 is a' side elevation or' the arrangement showniin Fig. 1; Fig 8is a section taken on line 3-3 F ig. 1; Figs, 4 and 5 are views similarto Figs.v l-,and 2 of a modiiication, and Figa@ is a radial sectionalview of a furthermodiicationj ln Figs. 1, 2 and 3 my invention isillustrated as applied to a bucket structure of the type wherein thebucket-carrying memfV ber 9, shown as being a wheel, hasa rim` lOwhiclrisprovided on opposite sides' with. annular concentric undercutgrooves providing ridges or projections 1.1 which slope or inclinetoward the center oi' the n'iein'ber);

At the base oi' rini 10 are shoulders 12. f The:l i

particular type may, according to one known` method, beasseinbled outhe/wheelriiifiby inaking the bucket base legs 14 suthcientlyi, wideapart that-ijshe same may-'be slippedra dially astraddle the rim 10`after which the legs are squeezed together and the buckets are movedradially to bring ridges 1li-and 11 into engagement. According tothismethod the entire'ring ot buckets is first-assembled around the wheel ina temporary manner and in correct spaced relation to each other, afterwhichthe bucket legs of each bucket are squeezed 'or pressed togethertoward the rim, the Abuckets at the same time) being displacedoutwardly, thereby interlocking ridges 11 and 15. Now, duringthisrsqueezing up operation, the metal ofthe` bucket base legs 'liowscircumferentially `and in some cases this has had the eliect of pressingad jacent buckets vtogether so tightly that stresses would be set up inthe vbucketring the bucket legs are squeezed togethouthe los ridges 15in moving radially outwardly,

slide up the outer surfaces of ridges 11` and are crushed up by saidridges,

'and the rici tion brought about by this action causes at times, ridges15 to liow circumferentially and engage so tightly the surta-:es o' thenext adjacent buckets as to prevent lthe radial movement of ridges l5 tocorrect posi tions under ridges 1l. The result is an im perfectinterlocking of ridges l5 and t1.

According to my invention, I overcome the above referred to diliicultiesby providing crushing strips 16 between the bucket bases which serve toreduce the area oiA contact between adjacent buckets so that rc`Agardless of the amount o'l pressure that may be applied on the sides oi"the buckets, stresses exceeding a predetermined value cannot be set upin the bucket ring since it' such stresses are. exceeded, strips l6 willbe crushed. At. the same time, the crushing strips 16 serve to spaceapart slightly adjacent buckets at the ends oi" the ridges 15 so thateven though such ridges do flow cir cumferentially somewhat duringthe'squcezing-up operation', they will not come into cngagement withadjacent buckets so as to prevent radially outward movement. In otherWords, ridges 15 Willjnot liow circumferentially sufiiciently during thesqueezing` up operations to frictionally engage, and lock themselvesagainst the next adjacent buckets.

By the provision of such crushing strips, therefore, I am enabled toguard against excessive stresses being set up in the bucket ring whenthe buckets are assembled utter the manner describedbut still l amenabled to obtain the desired degree of strcssdn the bucket ring. At thesame time .l overcome. a serious difficulty which. has hereto'l'ore beenencountered in assembling buckets on a rotor by the method re terred to,duc to the ridges kor projections on the bucket legs .flowing sidewiseand binding against adjacent bucket surfaces. l

After the bucket legs have been squeezed onto the wheel rim there aresmall spaces left between the inner end ol' the bucket legs andshoulders l2, and these spaces may be .filled by upsetting the ends olthe bucket legs. or the material of thel shoulders or by driii'ing in aseparate calking strip. lin the present instance, the spaces arc shownbeing filled by a separate calking 'strip 17.

Referring now to Figs. 4l; and 6, an inverted dovetail fastening meansis shown ot i thetypc wherein the buckets are put on the rim oi theWheel through filling slots and moved around into correct spacedrelation 'to'each other, the bases olE adjacent buckets vbeing broughtinto engagement with each other, or with suit-able spacing blockslocated between the bucket bases. 2() indicates a bucket wheel having' arim 2l provided with an annular head 22. which forms projections 23. Thebuckctslr are provided with U- shaped bases comprising legs 25 which.

straddle rim 2l and have projections 26 which lit under projections 23.At the base ola rim 2l are annular shoulders 2T against which the innerendsI olI bucket legs 25 rest, and at 25 are annular llangcs whichprevent tho bucket legs l'rom spreading laterally. lletwccn adjacentbuckets are crushing strips )l similar to crushing strips i6 ot ll`igs.l to Il and at the inner ends of the bucket base legs are crushingstrips 3l) located between. the bottoms of such legs and iianges 2S.

ln carrying out my invention inv connection with a wheel structure, asshown in Figs. l and 5, l lirst mount the ring of buckets on the wheelrim in the usual manner, the lilling openings being closed by blocks asis well understood. YVhen so assembled, the bucket bases are in niceengagement with each other. I. now take a suitable calking tool and calka number of the buckets at spaced intervals around the wheel so as toset up a tension in the buckets themselves` equivalent or substan tiallyequivalent to the stresses that will be applied by centrifugal torcewhen the machine is in operation. Stresses beyonid a predeterminedamount cannotrbe set up in the bucket ring by calking, however, asstrips 2S) will be crushed. I also calk the Wheel along the sidesurtaces of shoulders 27 so as to drive these shoulders out radially andbring projections 26 firmly into engagement with projections ,lfand byutilizing crushing strips il() l avoid the possibility oi setl100 tingup stresses of too great a value in rim 2l and the legs ot thel buckets.During this latter calking operation a small amount of material may beforced up or caused to flow into the spaces between crushing strips 3()105 as indicated at A in Fig. 5 and this assists in locking the. bucketsinto position.

Crushing strips 30 may extend either crosswise or circumferentially asfound de,-

sirable. ln Figs. 4 and 5 l have shown them 11o as estenihng crosswiscwhile in Fig. 6 l` have shown a modified arrangement in which theyextend circumferentially.

In Fig. 6, 20L indicates the bucket-carry ing member, 24 the buckets,and 29 and 115 30a the crushing strips corresj'ionding to crushingstrips 29 and $3() of Figs. 4 and 5. n this connection it will of coursebe obvious that crushing strips as shown at 30I and 30 in Figs. 4 to 6inclusive, may be 120 used in connection with a structure as shown inFigs. 1 to 3 inclusive if found desirable.

lln accordance `with the provisions o'l' the patent statutes, l havedescribed the prin- 125 ciple of loperation of my invention y with theapparatus which I n fdvv vonsiuer to represent 'the best 'embodimethereof, but l desire to have it understoodtthat the together .sui .Y iil, apparatus shown 1s only illustiative, and 130 ring having crushingpieces between adia-v cent buckets.

3. In ,anl elastic fluid turbine, a bucketlcarrying memberhaving a rim,and buckets having bases which straddle said rim, said buckets beingprovided with crushing strips which serve to limit the stresses set upin the bucket ring.

4. In an elastic fluid turbine, a bucketcarrying.' member having a rimwith ridges .thereong buckets which straddle said rim and havia ridgeswhich interlock with said 4first named ridges, and integral crushingstrips located between adjacent surfaces of the buckets.

5'. In van lelastic fluid turbine having a bucket-carrying memberprovided with a rim and shoulders, buckets having bases whichareattached to said rim and terminate at said shoulders, and crushingstrips between the bottoms of the bucket bases and said shoulders.

6. In an elastic fluid turbine having a bucket-carrying member providedwith a rim and shoulders, vbuckets having bases which are attached tosaid rim and terminate at said shoulders, crushing strips between thebottom of the bucket bases and said shoulders, and crushing stripsbetween adjacent surfaces of the buckets.

7'. In an elastic `lluid turbine, a bucket ring 'having buckets providedwith crushing strips along their sides and at' their bottoms.

In witness whereof, I have hereunto set my hand.

CHRIsTIAN -s'rniwsra-m

